//整数的取模 % 和除法 / 
#include <stdio.h>

#define D_TO_W 7

int main(void)
{
    int days;

    puts("Enter the number of days you want to convert (negative or zero to quit):");
    while(scanf("%d", &days) == 1 && days > 0)
    {
        printf("%d days are %d weeks, %d days.\n", days, days / D_TO_W, days % D_TO_W);
        puts("Enter the number of days you want to convert (negative or zero to quit):");
    }
    puts("Bye!");

    return 0;
}